1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and a computer-readable recording medium for processing an intraluminal image capturing an image of the inside of a lumen.
2. Description of the Related Art
Conventionally, endoscopes are popularly used as a medical observation apparatus introduced into the body of an examined subject (hereinafter, “subject”) such as a patient, to observe the inside of a lumen in the body. Also, in recent years, swallowed endoscopes (capsule endoscopes) have been developed that include, within a capsule-shaped casing, an image capturing device and a communication device that wirelessly transmits image data captured by the image capturing device to the outside of the body of the subject. It requires much experience to observe an image of the inside of the lumen in the subject's body (an intraluminal image) captured by such a medical observation apparatus and to make a diagnosis. Thus, medical diagnosis aiding functions that support medical doctors making a diagnosis are in demand. As an image recognition technique to realize such a function, a technique has been proposed by which an abnormal part such as a lesion is automatically detected from an intraluminal image so as to indicate an image on which an attention should be paid in a diagnosis.
To detect the abnormal part as described above, it is important to use a technique for performing, as pre-processing, a process of extracting unnecessary regions that are unnecessary for making a medical observation/diagnosis (e.g., a halation region in which a halation occurred, a dark part region showing the far side of the lumen, a contents region showing the contents such as the stool) and specifying a region that should be focused on such as a mucous membrane. For example, Japanese Patent Application Laid-open No. 2006-166939 discloses a technique for detecting, within an image, presence of a specific biological mucous membrane such as a lesion mucous membrane, without being affected by unnecessary regions such as a dark part. According to this publication, after some pixels corresponding to the unnecessary regions are eliminated based on color information of the pixels, the presence of the specific biological mucous membrane is detected.